dm: allow multiple --skp flags, allow single files
dm: allow multiple --skp flags, allow single files

Review URL: https://codereview.chromium.org/885353002

BrokenROM/external_skia,YUPlayGodDev/platform_external_skia,MinimalOS-AOSP/platform_external_skia,PAC-ROM/android_external_skia,geekboxzone/mmallow_external_skia,MinimalOS-AOSP/platform_external_skia,TeamExodus/external_skia,qrealka/skia-hc,nfxosp/platform_external_skia,spezi77/android_external_skia,scroggo/skia,timduru/platform-external-skia,google/skia,AOSPB/external_skia,shahrzadmn/skia,google/skia,scroggo/skia,YUPlayGodDev/platform_external_skia,HalCanary/skia-hc,TeamExodus/external_skia,tmpvar/skia.cc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,timduru/platform-external-skia,google/skia,invisiblek/android_external_skia,MarshedOut/android_external_skia,MonkeyZZZZ/platform_external_skia,Jichao/skia,geekboxzone/mmallow_external_skia,PAC-ROM/android_external_skia,nvoron23/skia,HalCanary/skia-hc,rubenvb/skia,nfxosp/platform_external_skia,nfxosp/platform_external_skia,MarshedOut/android_external_skia,UBERMALLOW/external_skia,geekboxzone/mmallow_external_skia,aosp-mirror/platform_external_skia,UBERMALLOW/external_skia,geekboxzone/mmallow_external_skia,MinimalOS-AOSP/platform_external_skia,UBERMALLOW/external_skia,rubenvb/skia,VRToxin-AOSP/android_external_skia,amyvmiwei/skia,rubenvb/skia,Igalia/skia,MinimalOS-AOSP/platform_external_skia,nfxosp/platform_external_skia,geekboxzone/mmallow_external_skia,PAC-ROM/android_external_skia,amyvmiwei/skia,noselhq/skia,TeamTwisted/external_skia,rubenvb/skia,TeamTwisted/external_skia,pcwalton/skia,tmpvar/skia.cc,Igalia/skia,OneRom/external_skia,BrokenROM/external_skia,TeamExodus/external_skia,samuelig/skia,aosp-mirror/platform_external_skia,boulzordev/android_external_skia,Infinitive-OS/platform_external_skia,noselhq/skia,MarshedOut/android_external_skia,vanish87/skia,tmpvar/skia.cc,qrealka/skia-hc,YUPlayGodDev/platform_external_skia,tmpvar/skia.cc,MonkeyZZZZ/platform_external_skia,TeamExodus/external_skia,Igalia/skia,MonkeyZZZZ/platform_external_skia,amyvmiwei/skia,PAC-ROM/android_external_skia,qrealka/skia-hc,ominux/skia,invisiblek/android_external_skia,Igalia/skia,TeamTwisted/external_skia,Igalia/skia,vanish87/skia,timduru/platform-external-skia,OneRom/external_skia,amyvmiwei/skia,PAC-ROM/android_external_skia,rubenvb/skia,AOSP-YU/platform_external_skia,Hikari-no-Tenshi/android_external_skia,AOSPB/external_skia,google/skia,TeamExodus/external_skia,vanish87/skia,pcwalton/skia,HalCanary/skia-hc,todotodoo/skia,Infinitive-OS/platform_external_skia,shahrzadmn/skia,AOSPB/external_skia,Igalia/skia,AOSP-YU/platform_external_skia,boulzordev/android_external_skia,OneRom/external_skia,todotodoo/skia,noselhq/skia,MonkeyZZZZ/platform_external_skia,tmpvar/skia.cc,Infinitive-OS/platform_external_skia,nvoron23/skia,YUPlayGodDev/platform_external_skia,Infinitive-OS/platform_external_skia,UBERMALLOW/external_skia,scroggo/skia,w3nd1go/android_external_skia,google/skia,AOSPB/external_skia,nvoron23/skia,w3nd1go/android_external_skia,todotodoo/skia,UBERMALLOW/external_skia,YUPlayGodDev/platform_external_skia,TeamExodus/external_skia,nvoron23/skia,rubenvb/skia,VRToxin-AOSP/android_external_skia,AOSP-YU/platform_external_skia,boulzordev/android_external_skia,UBERMALLOW/external_skia,Infinitive-OS/platform_external_skia,ominux/skia,MarshedOut/android_external_skia,YUPlayGodDev/platform_external_skia,rubenvb/skia,spezi77/android_external_skia,VRToxin-AOSP/android_external_skia,tmpvar/skia.cc,OneRom/external_skia,HalCanary/skia-hc,Jichao/skia,TeamTwisted/external_skia,boulzordev/android_external_skia,scroggo/skia,MonkeyZZZZ/platform_external_skia,w3nd1go/android_external_skia,geekboxzone/mmallow_external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,w3nd1go/android_external_skia,scroggo/skia,w3nd1go/android_external_skia,timduru/platform-external-skia,AOSP-YU/platform_external_skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,nfxosp/platform_external_skia,vanish87/skia,AOSP-YU/platform_external_skia,Jichao/skia,aosp-mirror/platform_external_skia,AOSPB/external_skia,VRToxin-AOSP/android_external_skia,AOSP-YU/platform_external_skia,spezi77/android_external_skia,tmpvar/skia.cc,ominux/skia,samuelig/skia,HalCanary/skia-hc,noselhq/skia,MonkeyZZZZ/platform_external_skia,geekboxzone/mmallow_external_skia,UBERMALLOW/external_skia,BrokenROM/external_skia,ominux/skia,HalCanary/skia-hc,shahrzadmn/skia,samuelig/skia,MinimalOS-AOSP/platform_external_skia,geekboxzone/mmallow_external_skia,rubenvb/skia,PAC-ROM/android_external_skia,qrealka/skia-hc,boulzordev/android_external_skia,VRToxin-AOSP/android_external_skia,shahrzadmn/skia,shahrzadmn/skia,BrokenROM/external_skia,AOSP-YU/platform_external_skia,todotodoo/skia,todotodoo/skia,MinimalOS-AOSP/platform_external_skia,nvoron23/skia,shahrzadmn/skia,TeamExodus/external_skia,BrokenROM/external_skia,pcwalton/skia,BrokenROM/external_skia,scroggo/skia,TeamTwisted/external_skia,nvoron23/skia,Infinitive-OS/platform_external_skia,TeamExodus/external_skia,qrealka/skia-hc,MinimalOS-AOSP/platform_external_skia,google/skia,samuelig/skia,samuelig/skia,TeamTwisted/external_skia,VRToxin-AOSP/android_external_skia,TeamTwisted/external_skia,timduru/platform-external-skia,aosp-mirror/platform_external_skia,AOSPB/external_skia,MonkeyZZZZ/platform_external_skia,BrokenROM/external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,pcwalton/skia,OneRom/external_skia,HalCanary/skia-hc,Infinitive-OS/platform_external_skia,vanish87/skia,nfxosp/platform_external_skia,Jichao/skia,vanish87/skia,Jichao/skia,noselhq/skia,MinimalOS-AOSP/platform_external_skia,google/skia,amyvmiwei/skia,AOSP-YU/platform_external_skia,pcwalton/skia,spezi77/android_external_skia,AOSPB/external_skia,amyvmiwei/skia,TeamTwisted/external_skia,ominux/skia,ominux/skia,MarshedOut/android_external_skia,amyvmiwei/skia,scroggo/skia,Igalia/skia,google/skia,invisiblek/android_external_skia,MonkeyZZZZ/platform_external_skia,nfxosp/platform_external_skia,vanish87/skia,boulzordev/android_external_skia,UBERMALLOW/external_skia,Jichao/skia,OneRom/external_skia,google/skia,ominux/skia,noselhq/skia,nvoron23/skia,timduru/platform-external-skia,amyvmiwei/skia,timduru/platform-external-skia,invisiblek/android_external_skia,boulzordev/android_external_skia,MarshedOut/android_external_skia,tmpvar/skia.cc,HalCanary/skia-hc,Jichao/skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,VRToxin-AOSP/android_external_skia,geekboxzone/mmallow_external_skia,noselhq/skia,nvoron23/skia,AOSP-YU/platform_external_skia,qrealka/skia-hc,VRToxin-AOSP/android_external_skia,OneRom/external_skia,VRToxin-AOSP/android_external_skia,vanish87/skia,Infinitive-OS/platform_external_skia,samuelig/skia,aosp-mirror/platform_external_skia,MonkeyZZZZ/platform_external_skia,spezi77/android_external_skia,qrealka/skia-hc,shahrzadmn/skia,aosp-mirror/platform_external_skia,pcwalton/skia,w3nd1go/android_external_skia,qrealka/skia-hc,shahrzadmn/skia,OneRom/external_skia,TeamTwisted/external_skia,TeamExodus/external_skia,noselhq/skia,pcwalton/skia,noselhq/skia,YUPlayGodDev/platform_external_skia,AOSPB/external_skia,boulzordev/android_external_skia,todotodoo/skia,nvoron23/skia,todotodoo/skia,todotodoo/skia,ominux/skia,nfxosp/platform_external_skia,tmpvar/skia.cc,Infinitive-OS/platform_external_skia,vanish87/skia,rubenvb/skia,samuelig/skia,w3nd1go/android_external_skia,AOSPB/external_skia,MarshedOut/android_external_skia,aosp-mirror/platform_external_skia,PAC-ROM/android_external_skia,Hikari-no-Tenshi/android_external_skia,shahrzadmn/skia,todotodoo/skia,MinimalOS-AOSP/platform_external_skia,pcwalton/skia,Jichao/skia,BrokenROM/external_skia,Jichao/skia,nfxosp/platform_external_skia,w3nd1go/android_external_skia,PAC-ROM/android_external_skia,HalCanary/skia-hc,pcwalton/skia,ominux/skia,scroggo/skia,boulzordev/android_external_skia,YUPlayGodDev/platform_external_skia,invisiblek/android_external_skia,invisiblek/android_external_skia,OneRom/external_skia,UBERMALLOW/external_skia,Igalia/skia,invisiblek/android_external_skia,PAC-ROM/android_external_skia,YUPlayGodDev/platform_external_skia,w3nd1go/android_external_skia,samuelig/skia,MarshedOut/android_external_skia,MarshedOut/android_external_skia,spezi77/android_external_skia,invisiblek/android_external_skia,rubenvb/skia